commonly described as “statutory performance indicators” or SPIs.6 The SPI data are collected and audited annually by the Audit Commission and are also published on government websites. BCS data are formally required for several of these indicators (Home Office, 2007): for example, in the set of SPIs defined for 2006–2007, “the percentage of people who think their local police do a good job” (SPI 2a), “perceptions of anti-social behaviour” (SPI 10b), and the violent crime rate (SPI 5b). Meeting these statutory guidelines requires that the BCS be regularly funded and capable of providing estimates at the local government level.
For more than three decades, the nation has had two national indicators of crime: the Uniform Crime Reporting program and the National Crime Victimization Survey. As described in Chapter 2, the two programs overlap in the crimes they cover (and both are used to generate national-level estimates of violent crime) but also differ in some important definitional ways. Despite the definitional differences between the two measures and their complementary nature, a fundamental question still arises in public discussions of crime statistics: Is it necessary to have two data systems for the purpose of estimating and evaluating trends in crime?
One part of that broader underlying question concerns the trends shown by the two series and the degree to which they agree or converge over time: In other words, do police records generally reflect victimization trends, and vice versa? A second part of the bigger question is more philosophical, concerning the necessity of two series: Does there remain the need for a second indicator completely independent of the official police reports?
The question about the concurrence of the NCVS and UCR trends is made more salient by the fact that there appears to have been a convergence in recent years of UCR- and NCVS-based national estimates of serious violent crime (i.e., rape, robbery, and aggravated assault). In other words, estimates from the NCVS of the number of crimes victims say they have reported to the police and the number that are recorded in the UCR program have grown closer in recent years (see Figure 3-2). On its face, the evidence of the most recent years of the series might suggest a redundancy—that national crime trends may be adequately described by UCR and that the NCVS role as a crime trend monitor may have diminished.
Additional information on best value performance indicators is available at http://www.bfpi.gov.uk/pages/faq.asp.